In this manner the shaft is driven upwards; logic and the facts of the case, in the absence of direct observation, justify the assertion.
If the root were to fail, and the reservoir of the intestine were exhausted, what would happen?
The following experiment will inform us: a larva is caught as it leaves the earth.

I place it at the bottom of a test-tube, and cover it with a column of dry earth, which is rather lightly packed.

This column is about six inches in height.

The larva has just left an excavation three times as deep, made in soil of the same kind, but offering a far greater resistance.

Buried under this short column of powdery earth, will it be able to gain the surface?
If its strength hold out the issue should be certain; having but lately made its way through the hard earth, this obstacle should be easily removed.
But I am not so sure.